Fish pens are generally constructed of fish netting that is formed to have a closed bottom, closed sides, and an open or closed top. A horizontal floating frame structure that lies flat on the ocean surface is used to shape the netting and provide a working platform. Weights are hung from the netting to provide draft and shape for the pen. Although these horizontal frame systems have been generally suitable for their purposes, they have several drawbacks.
When used in closed or protected waters, horizontal frame systems are visually objectionable, are inefficient in the use of pen volume, and tend to accumulate waste that pollutes the aquatic environment. While use of the pen system in open waters will avoid this pollution, the horizontal frame systems currently in use with these pen systems are not usable in open waters because of the roughness of the water and the unsteadiness of current flow. In particular, the surface-supported horizontal frames are subject to wave-induced forces, responding quickly to the passing of waves with violent motions that cause extreme stress on the structural components of the frame. Furthermore, the use of weights to shape the pen vertically is not compatible with the open water because water currents will move the weights, thus reducing the usable volume of the pen. In other words, the weights become less effective as current increases. As a result, the floating frame pen systems using suspended weights are limited to shallow, vertical configurations that can only be used in closed or protected waters where strong currents and wave conditions are not present. Hence, there is a need for a floating pen system that is stable enough to maintain a workable configuration without undue stress in large bodies of open water or bodies of water where strong currents are present.